Cross-flow fans



B. ECK ETAL Aug. 2, 1966 CROSS-FLOW FANS Filed Sept. 24, 1965 INVENTORS BRUNO ECK NIKO US LAING Wa/Q, 4 4

ATTADML'VQ United States Patent ,0

Claims. 61. 230-117 This invention relates to fans of the cross-flow type; the application is a continuation-in-part of our co-pending application Serial No. 221,622, filed September 5, 1962, now Patent No. 3,208,665, which is itself a continuationin-part of application No. 671,114, filed July 5, 1957, and now abandoned.

The invention is more especially concerned with fans of the cross-flow type wherein the guide means are within the rotor.

In a preferred form the invention provides a cross-flow fan wherein the guide means and rotor co-operate to set up a vortex of Rankine character having a generally cylindrical core region eccentric of the rotor axis, the vortex guiding the fiow in paths which are strongly curved about the core region.

The invention is specifically concerned with small fans for circulating air in inhabited spaces, e.g. rooms of a house, hotel or ofiice; in a typical example the fan may stand on a desk or table or hang on the wall of a room.

'Fans as just described will hereinafter for convenience be number machine of the cross-flow type can be made to produce in operation a satisfactory vortex of Rankine character and how by reason of the vortex good efi'iciency can be achieved. The relevant explanatory material in our prior applications is also contained in British Patents 876,611 and 876,612.

The invention provides a domestic fan of the cross-flow type comprising a support, a motor mounted on the support and comprising a fixed part and a rotating part cooperating therewith, a cylindrical bladed rotor defining an interior space and having one end secured to the rotating part of the motor coaxially therewith, and a single guide element mounted on the support to be held against rotation with the rotor extending substantially the length of the rotor within said interior space thereof the guide element as seen in cross-section being smoothly curved without interruption or inflection, the rotor and guide element co-operating on rotation of the rotor by said motor in a predetermined direction to induce a flow of air from an entry region through the path of the rotating blades to the interior of the rotor and thence again through the path of the rotating blades to a discharge region.

A domestic fan of the cross-flow type designed according to our recommendations can produce a surprisingly large throughput for a given size. The throughput for a given speed and diameter of rotor can be varied by varying the axial length of the fan. We have found that a throughput sufiicient for domestic air circulating purposes can be achieved with quite low speeds and diameters of rotor, for example a rotor of 60 mm. diameter rotating at 1500 r.p.m. or less. We have found that at low speeds and diameters the rotor can be light and has insufficient kinetic energy to hurt a persons hand if he accidentally touches the rotating rotor, nor will it normally be damaged if stopped in this way. Because of this the domestic fan according to the invention can have its rotor totally unprotected without danger of accident, and in this form "ice becomes a compact device of eifective performance which can be given an attractive appearance.

The motor can conveniently be of the type having an external armature, with the rotor being overhung-mounted thereon as a longitudinal extension thereof. The guide element can be a simple piece of sheet material formed to shape and mounted on the end of a support member extending axially through the motor and angularly adjustable to vary the outflow direction.

The invention will be further described with reference to one preferred embodiment thereof by way of example, this embodiment being illustrated in the accompanying diagrammatic drawings, in which:

FIGURE 1 is a perspective view of a table fan;

FIGURE 2 is a vertical longitudinal sectional view of the fan; and

FIGURE 3 is a transverse sectional view through the rotor, taken on the line IIIIII in FIGURE 2.

Referring to the drawings, the fan there shown comprises a fiat rectangular base 1 adapted to stand on a table and a pillar 2 upstanding from one end of the base. A stout horizontal support rod 3 extends through the pillar 2 and projects over the base 1 parallel to the length thereof. At its outer end the support rod 3 carries a knurled knob 4 by which it can be angularly adjusted by hand: friction between the support rod and the pillar 2 ensures that the rod remains in adjusted position. At its end ex tending over the base the support rod 3 mounts an internal stator 5 of an AC. induction motor designated generally 6. The rod 3 also carries the bearings 7 which [mount concave and forwardly curved in the direction of intended rotation shown by the arrow 11, and which as seen in cross-section (FIGURE 3) are arranged ini-a ring about the axis to define an interior space 12. The motor armature 8 includes a disc-like end portion 13 forming a closure for the motor end of the rotor 9, while the other end of the rotor is closed by an end disc 14, the blades 10 being mounted between the motor end portion 13 and theend closure disc 14. A guide element 15 in the form of a rectangular piece of sheet metal bent to arcuate formation 1 as seen in cross-section (FIGURE 3) has one end secured in a slot in the inner end of the support rod 3; thus the guide element is normally stationary but can be adjusted in angular orientation about the axis of the motor 6 and ing to roughly a of a semi-circle, the curve is conrotor 9 by manipulation of the knob 4. The guide element 15 as seen in cross-section has a curve approximattinuous and without inflection. The sides of the guide element 15 are well spaced from the envelope 16 defined by the inner edges of the blades 10, while the ends are close to the motor end portion 13 and end closure disc 14 respectively.

In operation of the fan, rotation of the rotor 9 by the motor 6 in the direction of the arrow 11 sets up a flow of air from an entry region E through the path of the rotating blades 10 of the rotor 9 to the interior space 12 thereof, and thence again through the path of the rotating blades to a discharge region D. The paths of air flow through the rotor are shown by the arrows F; air leaves the fan in the form of a smooth flowing jet or stream J. A vortex approximating very generally to Rankine type is set up, with a core region, i.e. a region of purely circulating flow, interpenetrating the path of the rotating blades about opposite the centre of the arc of the guide element 15; the core region is shown purely diagrammatically by the line V. The vortex assists in guiding the flow in the paths shown, which are curved about the vortex core V,

as appears in the drawing. The guide element 15 is curved approximately parallel to the path of flow due to the vortex. The formation of a vortex of Rankine type and the flow produced thereby is discussed further in British Patents 876,611 and 876,612 previously mentioned. Flow takes place in planes perpendicular to the rotor axis and flow in all such planes is substantially similar, except for interferences at the ends of the rotor.

As will be appreciated, the angular orientation of the guide element 15 defines the position of the entry and discharge regions E, D and the direction of the jet J.

The rotor '9 may have a relatively small diameter, say 60 mm., and a relatively low speed, say 1500 rpm, and will yet produce a satisfactory throughput of air. The throughput is on a first approximation proportional to the length of the rotor; thus within limits the designer can increase the length to obtain increased throughput without changing rotor diameter and speed. The rotor 9 is subject .only to light stresses and dimensional tolerances need not be close; a cheap, light construction is suflicient, e.g. in plastics material. The teachings of US. Patent 3,175,757 issued to Nikolaus Laing may be adopted. The small diameter, light construction and slow speed of the rotor enable its kinetic energy to be low enough so that if a ,persons fingers accidentally come into contact with the rotor they will not be hurt. For this reason the rotor needs no guard. Having neither guard nor exterior guide for the rotor the fan can be quite compact.

The fan described can be modified in various ways without departing from the invention. Thus the interior guide element 15 can be moulded of plastics material rather than formed of sheet material. To steady the rotor and guide element they can be connected by a journal bearing of [some sort at the end opposite the motor. The guide element could be supported on a pillar at the end of the rotor opposite the motor, instead of on the support rod 3. The

rotor end closure 14 would then be replaced by a stationary disc close to the end of the rotor, and the motor could be of normal internal armature type. These modifications are to be regarded simply as examples of possible variations of the fan illustrated.

.' We claim:

[ flection, the rotor and guide element co-operating on rotation of the rotor by said motor in a predetermined direction to induce a flow of air from an entry region through thepath of the rotating blades to the interior of the rotor and thence again through the path of the rotaing blades to a discharge region.

2. A fan as claimed in claim 1, wherein the guide element is a piece of sheet material formed to said curve.

3. A fan as claimed in claim 1, wherein the rotor at said one end is overhung-mounted on the rotating motor part and carries a closure at its other end and the guide element is mounted on a member carried by the support and extending axially through the motor to the interior of the rotor. I

4. A fan as claimed in claim 3, wherein said member mounting the guide element is angularly adjustable to vary the outflow direction.

5. A fan as claimed in claim 3, wherein the motor has its rotating part external of its fixed part and the rotor is overhung-mounted on the rotating part as a longitudinal extension thereof.

6. A domestic cross-flow fan comprising a support, a motor mounted on the support and having an internal part fixed thereto and an external part co-operating therewith and mounted for rotation thereabout, a bladed cylindrical rotor defining an interior space and overhung-mounted in coaxial relation on the rotating part of the motor and carrying a closure at the end opposite the motor, a single guide element extending substantially the length of the rotor within said interior space thereof the guide element as seen in cross-section being smoothly curved without interruption or inflection, and means mounting the guide element at the motor end of the rotor for angular adjustment of the element with respect to the support while preventing rotation of the element -with the rotor, the rotor and guide element co-operating on rotation of the rotor by said motor in a predetermined direction to induce a flow of air from an entry region through the path of the rotating blades to the interior of the rotor and thence again through the path of the rotating blades to a discharge region, angular adjustment of said guide element varying the outflow direction.

7. A fan as claimed in claim 6, wherein the guide element mounting means is a spindle extending axially through the motor.

8. A fan as claimed in claim 6, wherein the guide element is a piece of sheet material formed to said curve.

'9. A fan as claimed in claim 6, wherein the support comprises a base and a pillar upstanding therefrom with the fixed part of the motor mounted on the pillar in spaced relation to the base.

10. A fan as claimed in claim 9, wherein the axis of the motor and rotor is substantially horizontal.

References Cited by the Examiner UNITED STATES PATENTS 1,861,608 6/1932 Persons 230-117 2,053,425 9/1936 Else 230-259 2,942,773 6/1960 Eck 230 SAMUEL LEVINE, Primary Examiner.

HENRY F. RADUAZO, Assistant Examiner. 

1. A DOMESTIC CROSS-FLOW FAN COMPRISING A SUPPORT, A MOTOR MOUNTED ON THE SUPPORT AND COMPRISING A FIXED PART AND A ROTATING PART CO-OPERATING THEREWITH, A CYLINDRICAL BLADED ROTOR DEFINING AN INTERIOR SPACE AND HAVING ONE END SECURED TO THE ROTATING PART OF THE MOTOR COAXIALLY THEREWITH, AND A SINGLE GUIDE ELEMENT MOUNTED ON THE SUPPORT TO BE HELD AGAINST ROTATION WITH THE ROTOR EXTENDING SUBSTANTIALLY THE LENGTH OF THE ROTOR WITHIN SAID INTERIOR SPACE THEREOF THE GUIDE ELEMENT IS SEEN IN CROSSSECTION BEING SMOOTHLY CURVED WITHOUT INTERRUPTION OR INFLECTION, THE ROTOR AND GUIDE ELEMENT CO-OPERATING ON ROTATION OF THE ROTOR BY SAID MOTOR IN A PREDETERMINED DIRECTION TO INDUCE A FLOW OF AIR FROM AN ENTRY REGION THROUGH THE PATH OF THE ROTATING BLADES TO THE INTERIOR OF THE ROTOR AND THENCE AGAIN THROUGH THE PATH OF THE ROTATING BLADES TO A DISCHARGE REGION. 